The present invention is directed to anti-theft devices for fuel tanks, and, more particularly, concerns an anti-theft device which prevents fuel siphoning and provides for the measurement of fuel added to a fuel tank.
Fuel theft is not a new problem. Anti-theft devices have been developed in the past to prevent the siphoning of fuel from fuel tanks. For example, U.S. Pat. No. 3,951,297 describes an anti-siphon gas tank adaptor for use with large truck gasoline or diesel fuel tanks and which prevents the insertion of a siphoning tube into the tank.
Although these anti-siphoning devices effectively prevent the unauthorized removal of fuel from a fuel tank, they do not address a different type of fuel theft where the fuel never reaches the fuel tank. Modern commercial vehicle operators use company charge cards or charge accounts for purchasing fuel in large quantities, for example, fifty to two hundred gallons at a time. Unscrupulous vehicle operators have been known to make fuel charges for fuel which was not added to the fuel tank of their vehicle, but instead added to the fuel tank of an accomplice vehicle operator's vehicle for which the accomplice operator gives the unscrupulous operator a kickback for the fuel. Similarly, an unscrupulous vehicle operator may work with an accomplice service station attendant who will knowingly charge the unscrupulous operator for fuel not delivered and give the unscrupulous operator a kickback for the fraudulent fuel charge.
Unscrupulous vehicle operators or service station attendants can get away with this type of theft because it is difficult for companies to keep track of the exact amount of fuel required by each vehicle based on the number of miles driven. It is especially difficult to accurately predict fuel consumption of modern large diesel trucks having a two tank fuel system including fuel return lines from the engine to the fuel tanks. Such trucks may get anywhere between about five to eight miles per gallon depending on factors including how the truck is driven, the type of load being hauled, for example, a flat bed or a trailer, and the type of terrain traveled.
In light of the foregoing, a need exists for an improved anti-theft device which provides a means of insuring that the fuel reaches the fuel tank and is not siphoned from it subsequently.